Direction-finding antenna



1961 N. SHYHALLA El'AL 2,995,752

DIRECTION-FINDING ANTENNA Filed Jan. 29, 1960 NICHOLAS .SHYHALLA RICHARD J BL UM 2,995,752 DIRECTION-FINDING ANTENNA Nicholas Shyhalla, Niagara Falls, and Richard J. Blum,

Bulfalo, N.Y., assignors, by mesne assignments, to the United States of America as represented by the Secretary of the Navy Filed Jan. 29, 1960, Ser. No. 5,573 3 Claims. (Cl. 343-114) The present invention relates to direction-finding antennas and more particularly to very high frequency direction-finding antennas for use on aircrafts or missiles.

In the very high frequency range (30 to 300 megacycles) the coupling between the missile or airframe in which an antenna is mounted and the antennas become important where the antenna must be small with respect to wavelength. An example of such an antenna would be one that would fit inside a fifteen inch diameter missile of between two and three half-wavelengths long. If the whole system is visualized as radiating, the undesirable radiation contributed by the missile is very strong and overrides the radiation of the small directional antennas. As a result, the use of known antenna configurations would cause the missile to home (when used as a seeker) on ambiguous nulls.

An object of the present invention is the provision of an antenna system which is decoupled from its mount to eliminate interference from the mount.

Another object is to provide a receiving antenna for receiving signals in the very high frequency range without interference from the antenna mount.

A further object of the invention is the provision of an antenna system which is decoupled from its mount by means of antenna configuration and compensating elements.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawing wherein there is shown a preferred embodiment of the invention.

The antenna configuration shown is for receiving radio command signals for controlling a missile or aircraft in which the antenna configuration may be mounted. Antenna consists of three components for sense, rightleft, and up-down signals. The sense element of antenna 10 is a single symmetrical horizontal loop 11 and compensating element 26 located in the center of antenna 10. The output from loop 11 is fed to a balun (balance to unbalance transformer), not shown, by a two conductor balanced transmission line 12. The rightleft antenna consists of horizontal loops 13, 14 and vertical loops 18 and 19. Horizontal loops 13 and 14 and vertical loops 18 and 19 are symmetrically spaced about missile axis 16. Loops 13, 14 are connected diiferentially through a balanced two wire transmission line 17 to a balun, not shown. A pair of loops 18, 19 are mounted in a vertical plane and connected in parallel with loops 13, 14 to cancel the coupling between the missile body 21 and loops 13, 14. Loops 18, 19 are insensitive to horizontally polarized signals so they do not affect the antenna pattern for this polarization.

The up-down antenna consists of a pair of horizontal dipoles 22, 23 mounted symmetrically about center line 16 in a vertical plane. The output from dipoles 22, 23 is coupled out of phase through balanced two wire line 24.

Compensating element 26 is fastened to loop 11 at 27 to compensate for the capacitance between sense loop 11 and right-left loops 13, 14, 18, and 19.

In use, when antenna assembly 10 is pointed directly toward a radiating source, only sense element 11 provides an output since for this condition elements 13, 14 and 22, 23 are at the null. As the direction in which antenna 10 is pointed varies from the radiating source, error signals will be produced by the difference in signal strength received by elements 13, 14 or 22, 23. The output of loops 13, 14 represents the left-right error signal which is zero for straight ahead and is proportional to the difierence in the time of arrival of the radiating signal at loops 13 and 14. The output signal from dipoles 22, 23 represents up-down error signals and is obtained in the same manner as the left-right error signals. These error signals are fed to a control circuit, not shown, for controlling the flight of an aircraft or missile.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

What is claimed is:

1. A directional radio receiving antenna system for receiving very high frequency signals comprising a rectangular loop for sensing a beam of radio energy, a first pair of rectangular loops for sensing deviations from said beam of radio energy in the horizontal plane, a pair of dipoles for sensing deviations from said beam of radio energy in the vertical plane, a second pair of loops connected to said first pair of loops for cancelling any coupling between said first pair of loops and the mounting means for said antenna system and a U-shaped member connected to said first rectangular loop for compensating for the capacitance between said first horizontal loop and said first and second pairs of horizontal loops.

2. A directional radio receiving antenna system adapted to be mounted on an airframe for receiving very high frequency signals comprising a horizontal loop for sensing a beam of radio energy, first antenna means for sensing deviations from said beam in the horizontal plane, second antenna means for sensing deviations from said beam in the vertical plane, a U-shaped element connected to and perpendicular to said horizontal loop for compensating for the capacitance between said horizontal loop and said first antenna means, and additional compensating means connected to said first antenna means for decoupling said first antenna means from said antenna mount.

3. A directional radio receiving antenna system adapted to be mounted on an airframe for receiving very high frequency signals comprising first antenna means for sensing a beam of radio energy, a pair of horizontal loops mounted symmetrically about the airframe axis for sensing deviations from said beam in the horizontal plane, second antenna means for sensing deviations from said beam in the vertical plane, first compensating means connected to said first antenna means for compensating for the capacitance between said first antenna means and said pair of horizontal loops, and a pair of vertical loops mounted symmetrically about the airframe axis and connected in parallel with said horizontal loops for decoupling said horizontal loops from said antenna mount.

References Cited in the file of this patent UNITED STATES PATENTS 2,485,675 Taylor et a1 Oct. 25, 1949 

